Support loading Gosu classes/types by source in multiple ClassLoaders i.e. ,
the entire chain. With this change Gosu classes are guaranteed to load in the
same ClassLoader as Java classes declared alongside them.

Removing the old <> operator, you must use != instead.

Primitive types are now reserved keywords.

function double() {} // It won't compile

Variables declared in the using statement are implicitly final

using(var d = new Disposable())
{
d = null // It's now Illegal
}

Remove wildcards. Gosu allowed you to use Java-like wildcards but it never
supported them at the semantic level as, anyway, type parameters are covariant
in Gosu. Wildacards were just syntactic sugar as shown by the following
transformations:

from List<?> to List<Object>>

from List<? extends T> to List<T>>

from List<? super T> to List<UpperBound(T)>

The plugin is available from the JetBrains repository, which is directly accessible from your IntelliJ 12 plugins setup dialog. Select “Gosu”, right click and install (see this page more detailed instructions).